Starting mechanism

ABSTRACT

The housing of a starting motor rotatably mounts a cylinder having internal splines of one pitch. A shaft having external splines of a different pitch is rotatably and translatably supported by both the cylinder and housing and is connected at one end to a pinion engageable with the starter gear of an engine. Supported by the splines on the cylinder and the shaft are respectively a plunger and a nut that are advanced towards the pinion end of the shaft by the coaction of the cylinder and shaft with their respective different sets of splines. The plunger and nut are coupled by an axially acting clutch engaged by the translation of the plunger towards the pinion end and by a rotatably acting clutch engaged by rotation of the shaft relative to the cylinder. The rotatably acting clutch is disengaged by rotation of the shaft relative to the cylinder in the other direction or by the engagement of the axially acting clutch. Compressed between the nut and the pinion is a helical jump spring that not only translates the pinion when the nut is translated by the plunger but also allows the rotatably acting clutch to be disengaged should the teeth of the pinion abut those of the engine starter gear or should the engine starter gear drive the pinion rather than be driven by it. The jump spring also urges the pinion forward to engage the starter gear after the abutment has been eliminated. When the engine has started, the inertial interaction between the cylinder and plunger and a preload on the rotatably acting clutch retracts the plunger to engage another axially acting clutch that in turn retracts the pinion from engagement with the starter gear.

United States Patent Campbell Aug. 29, 1972 [54] STARTING MECHANISM [72]Inventor: Robert W. Campbell, Anderson,

. Ind. I

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed? May 17, 1971 [21] Appl. No.: 143,932

52 US. Cl. ..74/7 R 511 Int. Cl ..F02n 11/02 58 Field of Search ..74/7R, 7 c, 6

The housing of a starting motor rotatably mounts a cylinder havinginternal splines of one pitch. A shaft having external splines of adifferent pitch is rotatably andtranslatably supported by both thecylinder and housing and is connected at one end to a pinion engageablewith the starter gear of an engine. Supported by the splines on thecylinder and the shaft are respectively a plunger and a nut that areadvanced towards the pinion end of the shaft by the coaction of thecylinder and shaft with their respective different sets of splines. Theplunger and nut are coupled by an axially acting clutch engaged by thetranslation of the plunger towards the pinion end and by a rotatablyacting clutch engaged by rotation of the shaft relative to the cylinder.The rotatably acting clutch is disengaged by rotation of the shaftrelative to the cylinder in the other direction or by the engagement ofthe axially acting clutch. Compressed between'the nut and the pinion isa helical jump spring that not only translates the pinion when the nutis translated by the plunger but also allows the rotatably acting clutchto be disengaged should the teeth of the pinion abut those of the enginestarter gear or should the engine starter gear drive the pinion ratherthan be driven by it. The jump spring also urges the pinion forward toengage the starter gear after the abutment has been eliminated. When theengine has started, the inertial interaction between the cylinder andplunger and a preload on the rotatably acting clutch retracts theplunger to engage another axially acting clutch that in turn retractsthe pinion from engagement with the starter gear.

9 Claims, 1 Drawing Figure Patented Aug. 29, 1972 I l N VEN TOR. i052 zz ZZZ Cam 05M A T T R/VE Y STARTING MECHANISM This invention relates toa vehicle starting mechanism of the type having two differently pitchedhelically splined drive members that are clutchable to rotate andtranslate an output shaft.

Starting mechanism using pitched splines to effect engagement of apinion with the starter gear of an engine require an overrunning clutchwhere it is desired to protect the starting mechanism for the effects ofoverspeed created when the starting gear drives the pinion. Suchclutches, however, do not disengage the starting motor fromrotating thepinion when the teeth of the pinion abut those of the starter gear orwhen the engine fires but does not start and ejects the pinion. In eachof these conditions, if reengagement is subsequently attempted beforeboth the pinion or the ring gear have stopped, the pinion driven by thestarting motor, may possibly damage the starting gear by attacking ormilling it.

In the present invention a single rotatably acting clutch is employed todecouple the rotation of the starting motor from that of the shaftcarrying the pinion, not only when the teeth of the pinion abut those ofthe starting gear, but also when the pinion is driven by the engineafter the latter has started or when the engine fires without starting.Such decoupling is obtained by a plunger housing driven by the startingmotor and a shaft translating the pinion relative to the starting gear.A rotatably acting friction clutch couples the rotation of the plungerhousing to the shaft and is supported and controlled by a pair ofhelically splined drive members in the form of a plunger and a nut. Thecylinder translates and rotates the plunger through splines of a firstpitch, and the nut drives, or is driven by, the shaft through splines ofa second pitch. The plunger and nut are also connected by a pair ofaxially acting clutches, one such clutch being engageable to translatethe shaft toward the starting gear and the other clutch engageable toretract the shaft.

A helical jump spring is compressed between the nut and the pinion sothat the translation of the nut by the plunger is effective to translatethe pinion towards the starting gear. To prevent the nut fromtranslating to the starting motor end of the shaft and to allow thefriction clutch to be fully engaged by the torque transmitted throughthe effects of the differently pitched splines, Belleville springs arecompressed between the driving discs of the friction clutch and a stopshoulder on the motor end of the shaft. The Belleville springs preloadthe rotatably acting clutch so that the reaction between the splines onthe plunger and housing cooperate to retract the plunger, andtherethrough the shaft, when the engine starts and drives the pinion.

So that a slight forward translation of the nut relative to the plungerwill disengage the friction clutch, the driving discs of the frictionclutch are translatably connected to the plunger while the driven discsare fixed to the nut. Translation of the nut relative to the plunger todisengage the friction clutch is effected by a first axially actingclutch when the teeth of the pinion abut those of the starting gear orby the translation of the nut towards the pinion when the latter isdriven by the starting gear.

It is therefore a primary object of the present invention to provide arotary motion clutch that is disengageable to decouple the startingmotor from the starting gear of an internal combustion engine when thepinion on a translatable output shaft of the starting mechanism abutsthe starting gear and also when the starting gear drives the pinion.

It is another primary object of the present invention to provide astarting mechanism having a translatable output shaft to which rotarymotion is coupled from an input device by means of a clutch that istranslatable with and also relative to the shaft and that is engageableby translation in one direction relative to the shaft and disengageableby translation in the other direction.

It is a further object of the present invention to control thetranslation and engagement of a rotary clutch of the foregoing type by aplunger and a nut driveably connected respectively to the starting motorand translatable shaft by helical splines.

It is a further object of the present invention to provide a rotaryclutch controlled by splined plunger and nut members of the foregoingtype wherein one spring translates the shaft in response to thetranslation of the nut by the plunger and another spring translatablewith the shaft cooperates with the nut to engage and disengage theclutch.

Further details, objects and advantages of the present invention willbecome apparent from the following description taken in conjunction withthe single drawing which slows a longitudinal cross-section of anembodiment of the invention with the translatable shaft of the startingmechanism being shown in is retracted position.

With reference now to the drawing, there is shown an assembly 10 forcoupling the starting motor 12 to rotate the starter gear 14 of aninternal combustioneengine 16 by means of output means in the form of adrive pinion 18. Pinion 18 is affixed to one end of shaft 20 thatcarries Belleville springs 22 near the other end. Shaft 20 is translatedtowards starter gear 14 by a first axially acting clutch 24 and ahelical jump spring 26 and is retracted by a second axially actingclutch 28 and an antidrift spring 30. Axially acting clutch 24 comprisesa plunger or input member 32 and a nut or output member 34 that carry arotatably acting friction clutch pack 36 therebetween for coupling therotation of starting motor rotor 38 to a shaft 20 through input means inthe form of a plunger housing 40. The plunger housing 40 has a set ofquick pitch splines 42 for coating with plunger 32 to advance clutch 24.Shaft 20 has another set of splines 44 for backing nut 34 towardssprings 22 to engage clutch 36 and for advancing nut 34 to disengagethis clutch.

Assembly 10 is comprised of starting motor housing 46 suitably affixedto a drive housing 48, which in turn is suitably affixed to engine 16and has a hub 50 with a bore 52 therethrough. Rotatably and translatablyjournaled in bore 52 is a cup member 54 having bearings 56 securedthereto by snap rings 57 and 58. Cup 54 is press fitted on pinion end 60of shaft 20, the rotor end 62 of which is piloted in a drive hub 64 ofrotor 38. Drivably connected to the exterior of drive hub 64 by splines68 is plunger housing 40 having a cylinder 70 which is journaled bysleeve bearing 72 relative to drive housing 48 and is sealed relativethereto by suitable gland means 74.

A plurality of internal splines 42 of 70 right-hand pitch on cylinder 70mate with similar splines 43 on the exterior of plunger 32. Thesesplines couple the rotation of housing 40 to plunger 32. They also, whenrotated in a direction opposite to their sense, translate the plungerfrom a position determined by wall 76 of plunger housing 40,corresponding with the disengaged position of pinion 18, to a positiondetermined by snap ring 78 at the mouth of plunger sides 70,corresponding with the engaged position of pinion 18. When rotated inthe same direction as their sense, splines 42 and 43 translate theplunger to the disengaged position where it is maintained while rotor 38does not rotate by antidrift spring 30 compressed between snap ring 78in the mouth of cylinder 70 and a shoulder 80 on plunger 32.

A plurality of external splines 44 of 45 right-hand pitch on shaft 20mate with similar splines 45 on the interior of nut 34. These splinesnot only couple the rotation of nut 34 to shaft 20 but also, whenrotated in a direction opposite to their sense, translate nut 34 over alength greater than the translation of plunger 32 between its engagedand disengaged positions. Nut 34 will translate towards pinion end 60 ofshaft 20 when the interaction of the speed and splines thereof produce asufficient force on nut 34 to overcome a preload exerted thereon by jumpspring 26. Since it is desired to employ this mode of translating nut 34when pinion 18 is driven by starter gear 14, such as when engine 16 hasattained self-sustaining operation, the pitch of splines 44 and 45, aswell as the preload and spring rate of jump spring 26, are selected toeffect such translation only at speeds in excess of that at which rotor38 drivesshaft 20.

Friction clutch pack 36 is comprised of a plurality of driving discs 90and driven discs 92 the teeth of which are drivably connectedrespectively to drive splines 94 and 96 on plunger 32 and nut 34. Toenable Belleville springs 22 to apply the requisite normal force to theworking surfaces of the clutch pack 36, a Z-shaped circular clutchsupport plate 98 is splined to nut 34 and retained thereon by a snapring 100, and a clutch backplate 102 is splined to plunger 32 on therotor side of the clutch pack 36. Axial restraint for clutch backplate102 to initially preload and ultimately fully load clutch 36 is providedby Belleville springs 22 retained by snap ring 112 in shaft 20intermediate splines 44 thereon and rotor end 62 thereof by a collar 108having a radial flange l 10.

Plunger drive splines 94 are longer than the axial length of clutch pack36 to provide full drive connection therebetween when there is relativeaxial translation between plunger 32 and nut 34 upon forward translationof shaft 20 or operation of the clutch, as will be explained below. Withthis relative displacement between plunger 32 and nut 34 permitted bythe relative length of splines 94, clutch 36 is preloaded, loaded, andunloaded entirely with reference to shaft 20 by the action of jumpspring 26 acting on nut 34 and Belleville springs 22 acting on clutchplate 102.

The axial translation of plunger 32 relative to clutch discs 92 andclutch backplate 102 as well as relative to nut 34 is determined byfirst axially acting clutch 24 comprising circular flange 120 extendingradially inward from plunger 34 and a circular flange 122. The latterextends radially outward from clutch support plate 98 and is integraltherewith by an axial section 124. The outer diameter of flange 122 onone hand is less than the inner diameter of snap ring 78 by anamountsufficient to allow these elements to clear when translated to be injuxtaposition relative to each other. On the other hand, the outerdiameter of flange 122 is greater than the inner diameter of flange 120by an amount sufficient to allow the overlapping radial sections uponaxial abutment therebetween to effect both a first axially acting clutchand also a second friction clutch, clutch 36 being the first frictionclutch. Due to this overlap between flanges 120 and 122, the relativeaxial translation between plunger 32 and nut 34 is limited to the lengthof axial section 124. Moreover, further translation of plunger 32 causesflange 120 thereof to abut against flange 122 so as to prevent furtheraxial translation of plunger 32 relative to nut 34 in the direction ofpinion end 60. Subsequent to such abutment, further translation ofplunger 32 towards pinion end 60 results in the correspondingtranslation of nut 34 until flange 120 abuts against stop ring 78. Asdescribed in further detail below, such abutted translation of nut 34effects, through jump spring 26, the cor responding translation of shaft20 including cup 54, pinion 18, and Belleville springs 22 carriedthereby.

A second axially acting clutch 28 comprised of a seat in the rotor endof plunger 32 and circular flange 110 of collar 108 is engaged toretract shaft 20 and the elements carried thereby from the engagedposition to the disengaged position by the effects of theinertial forcescreated on splines 42 and 43 when the engine starts to drive shaft 20through ring gear 16 and pinion 18. When plunger 32 is thus translatedto the disengaged position, pinion 18 is disengaged from starter gear 14and retracted into the protective area within bore 52 of drive housing48.

OPERATION Upon commencement of rotation of rotor 38, plunger 32 iscaused to translate axially towards pinion end 60 through the inertialinteraction between splines 42 and 43. Part of the torque available fromrotor 38'is imparted to shaft 20 due to the preload exerted on theclutch by jump spring 26 and Belleville springs 22.

However, being slidably connected to plunger 32 by splines 94, drivingclutch pack 36 and clutch backplate 102 do not translate towards pinionend 60 until flange of plunger 32 engages and axially clutches flange122 of nut 34. Upon such clutch engagement, the translation of nut 34through flanges 120 and 122 is communicated to shaft 20 through jumpspring 26 and cup 54, thereby advancing pinion 18 towards starter orring gear 14.

Should this translation be interrupted, such as by the abutment of theteeth of pinion 18 with those of starter gear 14, the forward actingforces imparted to plunger 32 by rotation of plunger housing 40' andsplines 42 would be sufficient to continue the advancement of plunger32, and therethrough nut 34, until flange 120 abutted snap ring 78.However, such advancement would be opposed or cushioned by the furthercompression of spring 26. Moreover, since Belleville springs 22 beingafiixed to shaft 20 do not translate axially with plunger 32 when thereis tooth abutment, the continued translation of plunger 32 and nut 34towards pinion end 60 during such abutment completely unloads thepreload otherwise applied to clutch discs 90 and 92 by springs 26 and22. While clutch 36 is completely unloaded in this condition, theoverlapping and abutting radial surfaces of flanges 120 and 122 acts asa rotatably acting friction clutch to couple some slight torque fromrotor 38 to shaft 20. The overlap and torque transmitted therethrough isselected to overcome the normal force applied between pinion l8 andstarter gear 14 due to the increased force applied by the spring 26 uponabutment and to rotate or index the teeth of pinion 18 out of abutmentwith those of gear 14. Upon clearance of the interference between theteeth, jump spring 26 acting between nut 34 and cup 54 advances pinion18 from within bore 52 of housing 48 into full engagement with ring gear14. In this manner the radial and axial clutching actions effected byflanges 120 and 122 provide the dual functions of unloading and therebyprotecting clutch 36 during tooth abutment and also indexing pinion 18to eliminate the abutment.

The cranking of ring gear 14 by pinion 18 then commences with clutch 36being held in an engaged position determined by the abutment of flange120 of plunger 32 with snap ring 78. Moreover, since the contact betweenflanges 120 and 122 causes the translation of shaft 20 and the elementscarried thereby, as heretofore been described, flange 122 will bebrought directly under snap ring 78 when flange 120 is stopped thereby.With the pinion, clutches and plunger in this engaged position, theresisting torque represented by the nonstarted engine results in theapplication of a torque between shaft 20 and plunger housing 40 thatcauses splines 42 and 44 due to their different pitches to apply anaxial rearward jacking force on nut 34 and a forward jacking force onshaft 20. But, since the inertial reaction between the rotation ofplunger housing 40 and plunger splines 42 and 43 holds plunger 32against snap ring 78 and since, due to the difference in the pitches ofthe splines, this reaction is not overcome, plunger 32 is held in aposition fixed with respect to the cylinder 70. The effect of thejacking force is therefore not to translate nut 34 towards rotor end 62,because such translation is prohibited by the abutment of flanges 120and 122, but to cause a slight forward translation of shaft 20 relativeto nut 34. Such forward screwing of shaft 20 in nut 34 correspondinglytranslates Belleville springs 22 relative to nut 34 and therebyincreases the normal axial force applied by clutch backplate 102 to thedriving and driven clutch discs 90 and 92. This permits clutch 36 totransmit torques up to the limit determined by the deflectioncharacteristics of Belleville springs 22 and thereby allows the clutch36 to couple the full torques of rotor 38 less than this limit to pinion18.

Upon the tightening of clutch plates 90 and 92, pinion 18 cranks ringgear 14 to cause either a normal self-sustaining start of engine 16 or apartial start where the engine fires without attaining self-sustainingoperation. In either event starter gear 14 will drive, rather than bedriven by, pinion 18 at a speed greater than that normally developed byrotor 38. Provision is made to substantially unload clutch 36 and allowit to slip under the circumstances to protect clutch 36 as well as theinternal drive train and rotor 38 from the effects of overspeed. Thisslippage is effected by the inertial reaction between nut and shaftsplines 44 and 45 to translate nut 34 forward against jump spring 26 andaway from Belleville springs 22. Such translation is permitted and alsolimited by the length of arm 26 linking clutch support plate 98 withradial flange 122.

Thus, while the rearward translation of nut 34 relative to plunger 32 isstopped by the abutment of flange with flange 122 during engagement ofclutch 36, the forward translation of nut 34 relative to plunger 32 andtherefore shaft 20 is permitted to disengage the clutch. Such forwardtranslation of nut 34 is possible, even after flange 120 of plunger 32is stopped by snap ring 78, since the outer diameter of flange 122clears the inner diameter of both stop ring 78 as well as the bore 52 ofdrive housing 48. Flange 122 is therefore free to translate towardspinion end 60 for a distance determined by the length of arm 124.However, so that it does not limit the torque transmitted by clutch 36the length of arm 124 is selected to be greater than the axialseparation between nut 34 and collar 108 in their retracted positions,such separation in turn being greater than deflection between thepreloaded and fully loaded conditions of springs 22.

Retraction of pinion l8 iseffected by the inertial process, pinion 18 totheir disengaged positions. An-- A tidrift spring 30'thereaftermaintains plunger 32 and therethrough shaft 20 in their disengagedpositions against the motions of plunger 40 that might otherwiseinadvertently advance the shaft when starter motor 12 is deactivated.

Thus, one function of Belleville springs 22 is to allow clutch 36 tocouple torque from'rotor 38 to pinion 18 up to the limits determined bythe springs. Another function is to protect the clutch and the internaldrive train from torque transients in excess of these limits, as mightbe produced during a partial start or backfire condition. Anotherfunction, performed upon initial engagement of clutch 36 by the radialslippage of springs 22 with respect to clutch backplate 102, is toprotect the clutches and the drive train from the effects of torquetransients that would otherwise be experienced if the full kineticenergy of rotor 38 were coupled directly to shaft 20. Another importantfunction of springs 22 is to cooperate with jump spring 26 to maintain aminimum preload on clutch 36 when the engine is started and therebycouple sufficient torque to plunger splines 42 and 43 to effectretraction of shaft 20. This preload is selected sufficiently low toeffect a rate of retraction that avoids disengagement during a momentarypartial start. During this condition pinion 18, with continued crankingof starting motor 12, is quickly cycled from a driving, to a driven, andback to a driving mode with respect to starter gear 14 as clutch 36engages, slips, and reengages due to the translation of nut 34 relativeto springs 22. However, the preload on clutch 36, while it must effect aretraction rate through plunger splines 42 and 43 slow enough to avoiddisengagement during partial start operations, must be high enough toeffect disengagement for longer durations of overspeed.

Thus with both full and partial start conditions of overspeed as withtooth abutment, shaft and nut splines 44 and 45 screw nut 34 forward tofurther deflect jump spring 26 and relax Belleville springs 22. In thecase of overspeed, the translation of nut 34 relative to springs 22 islimited to retain a preload on clutch 36 while, in the case of toothabutment, translation of nut 34 relative to springs 22 is substantiallygreater to where clutch 36 is entirely unloaded.

Having described one embodiment of the present invention, it isunderstood that the specific terms and examples are employed in adescriptive sense only and not for the purpose of limitation. Otherembodiments of the invention, modifications thereof, and alternativesthereto may be used. I therefor aim in the appended claims to cover suchmodifications and changes as are within the true scope and spirit of myinvention.

What is claimed is:

1. In a starting mechanism:

. rotatable input means;

. rotatable and translatable output means;

. a plunger member and an output member;

. a first set of helical splines for operatively connecting said inputmeans with said plunger member to rotate and translate said plungermember, and a second set of splines for operatively connecting saidoutput member with said output means to rotate and translate said outputmeans;

e. first clutch means for selectively translating one said member withthe other said member;

f. second clutch means for selectively coupling the rotation of said onemember to said other member, said second clutch means translatable withsaid other member and engageable when said other member translates inone direction relative to said output means and disengageable when saidother member translates in the other direction relative to the outputmeans; and

g. spring means for engaging said second clutch means when said othermember translates in said one direction relative to said output meansand for restraining said translation of saidother member in said otherdirection.

2. In a starting mechanism for engaging rotatable means and drivable bythe rotor of a starting motor, said mechanism being supported along anaxis by a housing mountable in proximity to said rotatable means:

a. a cylinder rotatably mounted by said housing along said axis, saidcylinder being drivably connected with said rotor and having a firs setof helical splines;

. a shaft rotatably and translatably journalled along said axis by oneof said housing and cylinder, said shaft having a second set of helicalsplines and having drive means engageable with said rotatable means;

c. a plunger member received by one set of said splines and beingaxially translatable in response to rotation of said cylinder, and a nutmember received by the other of said splines and being axiallytranslatable relative to said drive means in response to rotation ofsaid shaft;

(1. axially acting clutch means connecting said plunger and nut membersfor causing said plunger member to translate said nut member;

e. rotary motion clutch means connecting said plunger and nut membersand being axially translatable by said nut member relative to said drivemeans, said rotary clutch means being disengageable by said axialtranslation of said nut member relative to said drive means and saidcylinder and being engageable by the translation of said shaft relativeto both said nut member and said cylinder; and

f. spring means for engaging said rotary clutch means when said shaft istranslated axially with respect to said nut member. I

3. In a starting mechanism for engaging rotatable means and drivable bythe rotor of a starting motor, said mechanism being supported along anaxis by a housing mountable in proximity to said rotatable means:

a. a cylinder rotatably mounted by said housing along said axis, saidcylinder being drivably connected with said rotor and having a first setof splines of a first predetermined pitch;

. a shaft rotatably and translatably journalled along said axis by oneof said housing and cylinder, said shaft having a second set of helicalsplines of a.

second predetermined pitch different from said first pitch and havingdrive means engageable with said rotatable means;

.C. a plunger member received by one set ofv said splines and beingaxially translatable in response to rotation of said cylinder, and a nutmember received by the other of said splines and being axiallytranslatable relative to said drive means in response to rotation ofsaid shaft;

(1. axially acting clutch means connecting said plunger and nut membersfor causing said plunger member to translate said nut member;

e. rotary motion clutch means connecting said plunger and nut member andbeing axially translatable by said nut member relative to said drivemeans, said rotary clutch means being disengageable by said axialtranslation of said nut member relative to said drive means and saidcylinder and being engageable by the translation of said shaft relativeto both said nut member and said cylinder and by said different pitchesof said splines; and

f. first spring means for engaging said rotary clutch means when saidshaft is translated axially with respect to said nut member; and

g. second spring means for urging said nut member towards said firstspring means from said drive means.

4. In a starting mechanism for engaging rotatable means and drivable bythe rotor of a starting motor, said mechanism supported along an axis bya housing mountable in proximity to said rotatable means;

a. a cylinder rotatably supported by said housing along said axis, saidcylinder being drivably connected with said rotor and having a first setof helical splines;

. a shaft rotatably and translatably journalled along said axis by oneof said housing and cylinder, said shaft having stop means, drive means,and a second set of helical splines therebetween, said drive meansengageable with said rotatable means;

0. a plunger member received by one set of said splines and beingaxially translatable in response to rotation of said cylinder, and a nutmember received by the other of said splines and being axiallytranslatable relative to said drive means in response to rotation ofsaid shaft;

. axially acting clutch means connecting said members for causing saidplunger member to translate said nut member;

. rotary motion clutch means connecting said 5. In a starting mechanismfor engaging rotatable c. a plunger member received by said splines ofsaid cylinder and being axially translatable in response to rotation ofsaid cylinder, and a nut member received by said set of splines on saidshaft and being axially translatable relative to said drive means inresponse to rotation of said shaft;

d. axially acting clutch means connecting said plunger and nut membersfor causing said plunger member to translate said nut member, saidaxially acting clutch means comprising a first flange extending radiallyfrom said plunger member towards said nut member and a second flangeextending radially from said nut member towards said plunger member,said second flange overlapping a radial portion of said first flange andaxially abuttable thereagainst whereby said axially acting clutch isengageable by translation of said plunger member;

means and drivable by the rotor of a starting motor, said mechanismsupported along an axis by a housing mountable in proximity to saidrotatable means:

a. a cylinder rotatably supported by said housing along said axis, saidcylinder being drivably connected with said rotor and having a first setof helical splines;

b. a shaft rotatably and translatably joumalled along said axis having asecond set of helical splines-and having drive means engageable withsaid rotatable means;

c. a plunger member received by said splines of said cylinder and beingaxially translatable'in response to rotation of said cylinder, and a nutmember received by said set of splines on said shaft and rotary motionclutch means connecting said plunger and nut members and axiallytranslatable by said nut member relative to said drive means, saidrotary clutch means disengageable by the axial translation of said nuttowards said drive said nut member from said drive means and f. springmeans restraining said axial translation of said nut member on saidshaft.

7. In a starting mechanism for engaging rotatable means and drivable bythe rotor of a starting motor, said mechanism supported alongan axis bya housing mountable in proximity to said rotatable means:

a. a cylinder rotatably supported by said housing means and engageableby the axial translation of being axially translatable relative to saiddrive means in response to rotation of said shaft;

d. axially acting clutch means connecting said rotary clutch meansconnecting said plunger and nut members and axially translatable by saidnut member relative to said drive means, said rotary clutch meansdisengageable by the axial translation of said nut member towards saiddrive means and engageable by the axial translation of said nut memberfrom said drive means.

6. In a starting mechanism for engaging rotatable along said axis, saidcylinder being drivably connected with said rotor and having a first setof helical splines;

. a shaft rotatably and translatably journalled along said axis having asecond set of helical splines and having drive means engageable withsaid rotatable means;

. a plunger member received by said splines of said cylinder and beingaxially translatable in response to rotation of said cylinder, and a nutmember received by said set of splines on said shaft and being axiallytranslatable relative to said drive means in response to rotation ofsaid shaft;

d. axially acting clutch means connecting said plunger and nut membersfor causing said plunger member to translate said nut member, saidaxially acting clutch comprising a first flange extending radially fromsaid plunger member towards said nut member and a second flangeextending radially from said nut member towards said plunger member,said second flange overlapping a radial portion of said first flange andaxially abuttable thereagainst, whereby said axially acting clutch ismeans and drivable by the rotor of a starting motor, said mechanismsupported along an axis by a housing mountable in proximity to saidrotatable means:

engageable by translation of said plunger member; rotary clutch meansconnecting said plunger and nut members and axially translatable by saidnut a. a cylinder rotatably supported by said housing along said axis,said cylinder being drivably connected with said rotor and having afirst set of helical splines;

b. a shaft rotatably and translatably joumalled along said axis having asecond set of helical splines and having drive means engageable withsaid rotatable means;

member relative to said drive means, said rotary clutch meansdisengageable by the axial translation of said nut member towards saiddrive means and engageable by the axial translation of said nut memberfrom said drive means;

. first spring means for engaging said rotary clutch means when saidshaft is translated axially with respect to said nut member; and

g. second spring means for restraining the translation 9. In a startingmechanism for engaging rotatable of said plunger relative to saidcylinder. means and drivable by the rotor of a starting motor, 8. In astarting mechanism for engaging rotatable said mechanism supported alongan axis by a housing means and drivable by the rotor of a startingmotor, tab e in proximity to Said rotatable means: said mechanismsupported along an axis by a housing 5 Cylinder l'otatably Supported ySaid housing mountable in proximity to said rotatable means: along saida Said y e being rivably 60 a. a cylinder rotatably supported by saidhousing nected with said Tom! and having a first set of along saidaxis,-said cylinder being drivably connected with said rotor and havinga first set of acting clutch is engageable by translation of saidplunger member;

. rotary clutch means connecting said plunger and v splines;

. a shaft rotatably and translatably joumalled along splines; said axishaving a second set of splines and having b. a shaft rotatably andtranslatably joumalled along drive means enga8eable with said rotatablemeanS said axis having a second set of splines and having a Plungerrecfewed by Sald spllnes of Sam drive means engageable with Saidrotatable means; cylinder and being axially translatable in response aplunger member received by said splines of said to Of and cylinder, anda nut member cylinder and being axially translatable in response 15 SamSet of Splmes Sad Shaft a to rotation of Said cylinder and a nut memberbeing axially translatable relative to said drlve received by said setof splines on said shaft and i resPonse to rotatlonofsald Sham. beingaxially translatable relative to said drive anally actmg clutch means pq means in response to rotation of said shaft; plunger and nut forcausing l plullger d axially acting clutch means connecting Saidmen'lberlto translate said nut member, said axially plunger and nutmembers for causing said plunger c fi g g gz T g; 8; member to translatenut member, towar S ag? nu member and ageco nd flange ex acting clutchmeans comprising a first flange tending radially from said nut membertowards tending radially from said plunger member 25 said plungermember, said second flange overtowards Said nut member a d a Secondflange lapping a radial portion of said first flange and axitendingradially from said nut member towar ally abuttable thereagainst, wherebysaid axially said plunger member, said second flange over? acting clutchis engageable by translation of said lapping a radial portion of saidfirst flange and axiplunger member; ally abuttable thereagainst, wherebysaid axially rotary clutch means connecting said plunger and nut membersand axially translatable by said nut member relative to said drivemeans, said rotary clutch means disengageable by the axial translationof said nut member towards said drive means and engageable by the axialtranslation of said nut member from said drive means:

. first spring means for engaging said rotary'clutch means when said nutmember is translated axially from said drive means;

. first spring means for engaging said rotary clutch 40 seFond Springmeans for subsiamiany fiisengagirfg means when said nut member istranslated axially Sald r ry clutch means when fotatloll of i from Saiddrive means; and shaft is above a predetermined speed; and

Second Spring means for disengaging Said rotary h. third spring meansfor restraining the translation clutch means when notation of Said Shaftis above a of said plunger member relative to said cylinder.predetermined speed.

1. In a starting mechanism: a. rotatable input means; b. rotatable andtranslatable output means; c. a plunger member and an output member; d.a first set of helical splines for operatively connecting said inputmeans with said plunger member to rotate and translate said plungermember, and a second set of splines for operatively connecting saidoutput member with said output means to rotate and translate said outputmeans; e. first clutch means for selectively translating one said memberwith the other said member; f. second clutch means for selectivelycoupling the rotation of said one member to said other member, saidsecond clutch means translatable with said other member and engageablewhen said other member translates in one direction relative to saidoutput means and disengageable when said other member translates in theother direction relative to the output means; and g. spring means forengaging said second clutch means when said other member translates insaid one direction relative to said output means and for restrainingsaid translation of said other member in said other direction.
 2. In astarting mechanism for engaging rotatable means and drivable by therotor of a starting motor, said mechanism being supported along an axisby a housing mountable in proximity to said rotatable means: a. acylinder rotatably mounted by said housing along said axis, saidcylinder being drivably connected with said rotor and having a first setof helical splines; b. a shaft rotatably and translatably journalledalong said axis by one of said housing and cylinder, said shaft having asecond set of helical splines and having drive means engageable withsaid rotatable means; c. a plunger member received by one set of saidsplines and being axially translatable in response to rotation of saidcylinder, and a nut member received by the other of said splines andbeing axially translatable relative to said drive means in response torotation of said shaft; d. axially acting clutch means connecting saidplunger and nut members for causing said plunger member to translatesaid nut member; e. rotary motion clutch means connecting said plungerand nut members and being axially translatable by said nut memberrelative to said drive means, said rotary clutch means beingdisengageable by said axial translation of said nut member relative tosaid drive means and said cylinder and being engageable by thetranslation of said shaft relative to both said nut member and saidcylinder; and f. spring means for engaging said rotary clutch means whensaid shaft is translated axially with respect to said nut member.
 3. Ina starting mechanism for engaging rotatable means and drivable by therotor of a starting motor, said mechanism being supported along an axisby a housing mountable in proximity to said rotatable means: a. acylinder rotatably mounted by said housing along said axis, saidcylinder being drivably connected with said rotor and having a first setof splines of a first predetermined pitch; b. a shaft rotatably andtranslatably journalled along said axis by one of said housing andcylinder, said shaft having a second set of helical splines of a secondpredetermined pitch different from said first pitch and having drivemeans engageable with said rotatable means; c. a plunger member receivedby one set of said splines and being axially translatable in response torotation of said cylinder, and a nut member received by the other ofsaid splines and being axially translatable relative to said drive meansin response to rotation of said shaft; d. axially acting clutch meansconnecting said plunger and nut members for causing said plunger memberto translate said nut member; e. rotary motion clutch means connectingsaid plunger and nut members and being axially translatable by said nutmember relative to said drive means, said rotary clutch means beingdisengageable by said axial translation of said nut member relative tosaid drive means and said cylinder and being engageable by thetranslation of said shaft relative to both said nut member and saidcylinder and by said different pitches of said splines; and f. firstspring means for engaging said rotary clutch means when said shaft istranslated axially with respect to said nut member; and g. second springmeans for urging said nut member towards said first spring means fromsaId drive means.
 4. In a starting mechanism for engaging rotatablemeans and drivable by the rotor of a starting motor, said mechanismsupported along an axis by a housing mountable in proximity to saidrotatable means; a. a cylinder rotatably supported by said housing alongsaid axis, said cylinder being drivably connected with said rotor andhaving a first set of helical splines; b. a shaft rotatably andtranslatably journalled along said axis by one of said housing andcylinder, said shaft having stop means, drive means, and a second set ofhelical splines therebetween, said drive means engageable with saidrotatable means; c. a plunger member received by one set of said splinesand being axially translatable in response to rotation of said cylinder,and a nut member received by the other of said splines and being axiallytranslatable relative to said drive means in response to rotation ofsaid shaft; d. axially acting clutch means connecting said members forcausing said plunger member to translate said nut member; e. rotarymotion clutch means connecting said plunger and nut members and axiallytranslatable by said nut member relative to said drive means, saidrotary clutch means disengageable by further axial translation of saidnut member than of said drive means and engageable by further axialtranslation of said shaft than of said nut member; and f. spring meansfor aiding said plunger member to translate said stop means.
 5. In astarting mechanism for engaging rotatable means and drivable by therotor of a starting motor, said mechanism supported along an axis by ahousing mountable in proximity to said rotatable means: a. a cylinderrotatably supported by said housing along said axis, said cylinder beingdrivably connected with said rotor and having a first set of helicalsplines; b. a shaft rotatably and translatably journalled along saidaxis having a second set of helical splines and having drive meansengageable with said rotatable means; c. a plunger member received bysaid splines of said cylinder and being axially translatable in responseto rotation of said cylinder, and a nut member received by said set ofsplines on said shaft and being axially translatable relative to saiddrive means in response to rotation of said shaft; d. axially actingclutch means connecting said plunger and nut members for causing saidplunger member to translate said nut member, said axially acting clutchmeans comprising a first flange extending radially from said plungermember towards said nut member and a second flange extending radiallyfrom said nut member towards said plunger member, said second flangeoverlapping a radial portion of said first flange and axially abuttablethereagainst, whereby said axially acting clutch is engageable bytranslation of said plunger member; and e. rotary clutch meansconnecting said plunger and nut members and axially translatable by saidnut member relative to said drive means, said rotary clutch meansdisengageable by the axial translation of said nut member towards saiddrive means and engageable by the axial translation of said nut memberfrom said drive means.
 6. In a starting mechanism for engaging rotatablemeans and drivable by the rotor of a starting motor, said mechanismsupported along an axis by a housing mountable in proximity to saidrotatable means: a. a cylinder rotatably supported by said housing alongsaid axis, said cylinder being drivably connected with said rotor andhaving a first set of helical splines; b. a shaft rotatably andtranslatably journalled along said axis having a second set of helicalsplines and having drive means engageable with said rotatable means; c.a plunger member received by said splines of said cylinder and beingaxially translatable in response to rotation of said cylinder, and a nutmember received by said set of splines on said shaft and being axiallytranslatable relative to said drive means in respoNse to rotation ofsaid shaft; d. axially acting clutch means connecting said plunger andnut members for causing said plunger member to translate said nutmember, said axially acting clutch means comprising a first flangeextending radially from said plunger member towards said nut member anda second flange extending radially from said nut member towards saidplunger member, said second flange overlapping a radial portion of saidfirst flange and axially abuttable thereagainst whereby said axiallyacting clutch is engageable by translation of said plunger member; e.rotary motion clutch means connecting said plunger and nut members andaxially translatable by said nut member relative to said drive means,said rotary clutch means disengageable by the axial translation of saidnut towards said drive means and engageable by the axial translation ofsaid nut member from said drive means and f. spring means restrainingsaid axial translation of said nut member on said shaft.
 7. In astarting mechanism for engaging rotatable means and drivable by therotor of a starting motor, said mechanism supported along an axis by ahousing mountable in proximity to said rotatable means: a. a cylinderrotatably supported by said housing along said axis, said cylinder beingdrivably connected with said rotor and having a first set of helicalsplines; b. a shaft rotatably and translatably journalled along saidaxis having a second set of helical splines and having drive meansengageable with said rotatable means; c. a plunger member received bysaid splines of said cylinder and being axially translatable in responseto rotation of said cylinder, and a nut member received by said set ofsplines on said shaft and being axially translatable relative to saiddrive means in response to rotation of said shaft; d. axially actingclutch means connecting said plunger and nut members for causing saidplunger member to translate said nut member, said axially acting clutchcomprising a first flange extending radially from said plunger membertowards said nut member and a second flange extending radially from saidnut member towards said plunger member, said second flange overlapping aradial portion of said first flange and axially abuttable thereagainst,whereby said axially acting clutch is engageable by translation of saidplunger member; e. rotary clutch means connecting said plunger and nutmembers and axially translatable by said nut member relative to saiddrive means, said rotary clutch means disengageable by the axialtranslation of said nut member towards said drive means and engageableby the axial translation of said nut member from said drive means; f.first spring means for engaging said rotary clutch means when said shaftis translated axially with respect to said nut member; and g. secondspring means for restraining the translation of said plunger relative tosaid cylinder.
 8. In a starting mechanism for engaging rotatable meansand drivable by the rotor of a starting motor, said mechanism supportedalong an axis by a housing mountable in proximity to said rotatablemeans: a. a cylinder rotatably supported by said housing along saidaxis, said cylinder being drivably connected with said rotor and havinga first set of splines; b. a shaft rotatably and translatably journalledalong said axis having a second set of splines and having drive meansengageable with said rotatable means; c. a plunger member received bysaid splines of said cylinder and being axially translatable in responseto rotation of said cylinder, and a nut member received by said set ofsplines on said shaft and being axially translatable relative to saiddrive means in response to rotation of said shaft; d. axially actingclutch means connecting said plunger and nut members for causing saidplunger member to translate said nut member, said axially acting clutchmeans comprising a first flange extending radially from said plungermember towArds said nut member and a second flange extending radiallyfrom said nut member towards said plunger member, said second flangeoverlapping a radial portion of said first flange and axially abuttablethereagainst, whereby said axially acting clutch is engageable bytranslation of said plunger member; e. rotary clutch means connectingsaid plunger and nut members and axially translatable by said nut memberrelative to said drive means, said rotary clutch disengageable by theaxial translation of said nut member towards said drive means andengageable by the axial translation of said nut member from said drivemeans; f. first spring means for engaging said rotary clutch means whensaid nut member is translated axially from said drive means; and g.second spring means for disengaging said rotary clutch means whenrotation of said shaft is above a predetermined speed.
 9. In a startingmechanism for engaging rotatable means and drivable by the rotor of astarting motor, said mechanism supported along an axis by a housingmountable in proximity to said rotatable means: a. a cylinder rotatablysupported by said housing along said axis, said cylinder being drivablyconnected with said rotor and having a first set of splines; b. a shaftrotatably and translatably journalled along said axis having a secondset of splines and having drive means engageable with said rotatablemeans; c. a plunger member received by said splines of said cylinder andbeing axially translatable in response to rotation of said cylinder, anda nut member received by said set of splines on said shaft and beingaxially translatable relative to said drive means in response torotation of said shaft; d. axially acting clutch means connecting saidplunger and nut members for causing said plunger member to translatesaid nut member, said axially acting clutch means comprising a firstflange extending radially from said plunger member towards said nutmember and a second flange extending radially from said nut membertowards said plunger member, said second flange overlapping a radialportion of said first flange and axially abuttable thereagainst, wherebysaid axially acting clutch is engageable by translation of said plungermember; e. rotary clutch means connecting said plunger and nut membersand axially translatable by said nut member relative to said drivemeans, said rotary clutch means disengageable by the axial translationof said nut member towards said drive means and engageable by the axialtranslation of said nut member from said drive means: f. first springmeans for engaging said rotary clutch means when said nut member istranslated axially from said drive means; g. second spring means forsubstantially disengaging said rotary clutch means when rotation of saidshaft is above a predetermined speed; and h. third spring means forrestraining the translation of said plunger member relative to saidcylinder.